Ringer clapper assembly



J. F. HOUDEK, JR 3,172,100

RINGER CLAPPER ASSEMBLY Filed Dec. 22. 1960 45a 7'/ March 2, 1965 J x an i 254,

United States Patent O 3,172,100 RHNGER CLAPPER ASSEMBLY Joseph F. Handelt, Jr., Elmhurst, Ill., assigner to International Telephone and Telegraph Corporation Filed Dec. 22, 1960, Ser. No. 77,533 5 Claims. (Cl. S40- 401) This invention relates to apparatus for use in telephone systems and more particularly to frequency selective ringers for use on party lines.

In known frequency selective ringers, both the electrical and the mechanical systems are tuned for a designated frequency, commonly frequencies between sixteen and two-thirds and sixty-six and two-thirds cps. The electrical tuning is accomplished by selecting a capacitor that resonates with the magnet coil at the desired frequency. The mechanical tuning can be accomplished by varying the inertia of the armature assembly and/ or the stiffness of the clapper shaft or the reed spring assembly used to attach the armature to the frame. Some ringers ut-ilize as the clapper, the weight used as an inertia means for tuning the ringer; others attach a separate tuning weight to the clapper rod; and still others use a dual tuned system wherein the tuning weight and the clapper are on separate stems attached to the armature. Where a weight is used both as an inert-ia means and as a clapper, the sound quality cannot be controlled, since the position of the clapper is then determined by the frequency required and cannot be adjusted to obtain the maximum sound output. The weight also tends to dampen the gongs because of its size and inertia. When a separate weight is attached to the clapper rod to control the frequency, there still remains this tendency to dampen the gongs. Even when a dual tuned system wherein both the clapper assembly and a separate weight assembly are attached to the armature is used gong damping can occur because of the total inertia of the armature assembly.

Mechanical tuning results from the vibratory reactions between the moment of inertia of the mass attached to the flexible stem and the combined spring constants of the stem and the reed spring by which the armature is attached to the frame. The moment of inertia is, of course, dependent upon both mass and the radius around the center of rotat-ion. The amplitude of the movement of the mechanically tuned system is a function of those forces such as friction which dampen every such system. Thus, sensitivity and selectivity are determined primarily by the relative quantities of the moments of inertia, the spring constants and the damping contained in the mechanically tuned system. The stability of the system is determined by the capability of the component parts to resist changes due to wear and the amount of damping present. The sound quality is a function of clapper position and inertia.

Therefore, it is an object of this invention to provide new an-d improved ringers with pleasing tones while maintaining a high level of sensitivity.

Another object of this invention is to provide a ringer which is stable with respect to time and use. In this connection, an object of this invent-ion is to provide highly selective harmonic ringers with good sound quality.

And yet another object of this invention is to provide a harmonic ringer that is compact, economical to manufacture and provides pleasing tone.

In accordance with one aspect of this invention, a dual stem tuned system is used wherein one of the stems, a clapper shaft is permanently attached not to an armature, but to a frame. The other stem (a drive rod) which is part of a tuned driving system is attached to the armature. This results in a ringer with good frequency sensitivity, since the lightweight clapper shaft has a much higher amplitude swing than the drive rod and, therefore, has a Edili@ Patented Mar. 2, 1965 tendency to strike its associated gongs with a lower input voltage.

Improved frequency stability results because the clapper assembly which is driven by the tuned drive unit also acts to dampen the drive unit, therefore the excursion of the drive unit is less dependent upon the driving volage variations. The frequencies of the two tuned systems, that is the clapper assembly and the drive unit, are such that no false signaling due to sum and difference frequencies occurs. The driving unit is tuned by varying both the position and size of a weight and by varying a reed spring associated with the armature to provide a highly selective ringer. Pleasing tones are available because the clapper can be sized and adjusted to strike the gongs in a position which gives the greatest sound output. Also, gong damping is minimized by the light weight of the clapper assembly, since the direction of the clapper swing is more easily and speedily changed because of its low inertia. Also, since the amplitude of the swing of both systems is relatively constant and because of the mutual damping caused by the force coupling of the systems, there is only a slight variation in the impact forces upon the gongs with changes in voltage amplitude.

The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with t'he accompanying drawings, wherein:

FIG. 1 is a top view of the ringer;

FIG. 2 is a bottom view looking upward (as Viewed in FIG. l) along line 2 2 of FIG. l;

FIG. 3 is a side view of the ringer taken along line 3-3 to illustrate the placement of the drive rod and clapper shaft assembly;

FIG. 4 is a perspective view of the drive rod and clapper shaft assembly, per se;

FIG. 4 is a detailed drawing of the clapper subassembly;

FIG. Sa is a top view of the shaft of the clapper assembly showing the manner in which the shaft is twisted; and

FIG. 6 is a detailed drawing of the armature and drive rod sub-assembly.

The ringer disclosed in the drawings is an improvement over the ringer shown in my Patent No. 2,844,767 for Telephone Substation Ringers assigned to the assignee of this application.

Referring to the drawings, an exemplary frequency selective ringer of the type under discussion is shown as including a drive mechanism DM, a pair of gongs G and a drive rod and clapper assembly A. The drive mechanism DM comprises a frame 2 upon which is mounted an electromagnet comprising a coil 4 and an L-shaped core 5, a permanent magnet 6, the pair of gongs G, and the drive rod and clapper assembly A. The frame 2 and gongs G are made of a non-magnetic material such as aluminum or brass; and core 5 preferably consists of a plurality of laminations of magnetic material rigidly secured together by tabs 7. The core is mounted onto a non-magnetic slide plate 8 which is adjustably secured to frame 2 by means of screw 9 passing through an elongated opening 10 in slide plate 8. As indicated in FIGS. l and 2, tabs 7 are integral parts of plate 8.

To complete the magnetic circuit, an L shaped shunt bar 11, which is constructed of magnetic material, is aflixed to frame 2 by means of screw 12. Shunt bar 11 includes two arms 15 and 16 interconnected by intermediate section 17. These two arms terminate in lips 21 which overlappingly engage the extremities of core whereby, the LV shaped core and the L shaped shunt bar generally form a rectangle.

Magnetic biasing means such as permanent magnet 6 is' attached by' its ownmagiieticuxto'shunt bar 11 and held in position by screws 22, legs 23 connected to frame 2, and a crossbar Z'i'niade of non-magnetic material which forms a bracket for magnet' 6. As will become more apparent from the following description, this permanent magnet polarizes the magnetic circuit.

The" drive rod and clapper assembly A includes an armature 2S, a clapper assembly 2'6, and a drive rod assembly 27. Thev armature 25', also L shaped, comprises an upper arm 25a alower arm 25D, and an interconnecting section 28 which is opposite permanent magnet 6. The il shaped core and the Al`. shaped armature are' cooperatively arranged to generally form a rectangle. ideally this rectangle should be a` perfect square so that the flux paths are of equal length regardlessy of which end of -the core is the north pole. Practical space limitations, however, make it necessary to make the side of the core, and hence the corresponding side of the armature 25b upon which the magnet coil is mounted, slightly longer. This difference in length should' be kept to a minimum. The ends of the armature cooperate with the ends of the core to provide operating air gaps g1, g2 at diagonally opposed corners.

Meanspsuch as a reed spring 34 is provided for movably supporting the armature 25. The bottom of spring 34 is attached to frame 2 through a bracket 3d and screws 37. The top of spring 34is attached to armature 25 through a bracket38 and screws or rivets 39. In this manner thefarmature is given a turning movement when the spring 34'bends. The drive rod assembly 27 is permanently attached to the bracket 33v by means such as welding or knurling. An inertia means such as' weight 40 is adjustably attached to the driving r'od 27 by means of set screw 41. Driven means consisting of the clapper assembly 26 is fixably attached to the bracket 36 at end 36a also either' by welding or knurling. The clapper assembly is made up of a flexible shaft 45 and a clapper 46 and is permanently attached to frame 2 by bracket 36.

From an inspection of the drawing it will be apparent that the drive rod assembly 27 vis attached tothe frame via the fiexiblecoupling of the spring 34 and that the clapper is attachedl to the frame via the flexible coupling of the shaft 45. The flexible shaft 45 fits behind and mechanically engages the shaft of the drive rod, thus adding its spring bias toV thebias ofthe coupling spring 34. Therefore, the springs 45, 34 push against each other. The drive rod is driven by the magnetic flux of the coil 4 acting on the armature 2S and the clapper is driven by the motion of the driving rod acting through the mechanicall engagement between the rod and shaft at point 4.

As the rod and shaft of assembly A swing to and fro in a pendulum motion there will be times when the shaft 45 swings away from the drive rod 27, times when the two move together as a unit, and times when the flexible shaft tends to wrap around the drive rod. if a metal to metal contact were permitted, there would be a clicking noise as the rod and shaft collide, one gong would be struck slightly harder than the other gong, the flexibility of the shaft 45 would change' during its swings as it collides with the rod, and further the shaft 45 would tend to develop both a random whipping motion and a harmonic motion in addition toA the fundamental motion established by the total length of the shaft. These problems could be 4tolerated and would not cause any serious detrimental effect, however, to avoid these problems and to further improve the ringer an elastic sleeve is fitted over the drive shaft at the point x where the shaft and rod collide. This sleeve damps mechanical motion of the shaft relative to the rod at that point.

The exact physical dimensions of the components of assembly A may be conveniently determined by empirical methods. However, in one exemplary construction there where satisfactory results when the length l1 (FIG. 5) was 2.786 inches, and the length I2 was 1.156 inches. The diameter d was .468 inch for driving frequencies ranging from zero to forty-two cpis. and .375 inch for driving frequencies betweeny forty-two and ysixty-six` and twothirds c.p.s. Thefthickness tlwas .057 inch and the thickness t2 was .213 inch. The upper end of the shaft is bent away at an angle dof 5 to 10 from astraight line extension of the lower end and twisted at point x by an angle b of approximately 177. ln the exemplary coristruction the shaft 45 was Phosphor bronze (Alloy A), spring temper .0453 diameter, the clapper 46 was brass, and the sleeve on the driving rod`27 at point x was silicon rubber tubing (Moxnes Products Inc. #51).

The weight 4t! and the drive rod were of any convenient size and material with the weight being adjustably positioned up or down on the' drive rod'to tune the mechanicalv assembly A to vibrate at the frequency of the electrical driving wave applied to the coil 4l Preferably this frequency is much lower than the resonant frequency of the clapper assembly (FlG. 5). rfhe rod was substantially rigid. The small angle of bend in the drive rod at point x which is most apparent in FiG. 3 is provided merely to give clearance between the weight and the gongs G so that the weight does not strike either gong at any time.

Preferably the spring 34 is selected according to the tuned frequency of the assembly A. Again, thecharacteristics of this spring will be determined empirically according to the effects that are desired.

The ringer operates in the following manner. The magnet 6 normally polarizes the core 5 so that its ends are north magnetic poles, in the exemplary construction, and polari'zes the armature so that its ends 25a, 25b are south magnetic poles. Thus, the ends of the armature and core normally exert equal force on each other and the clapper does not touch either of the gongs G.

When energized by an alternating current of suitable frequency, electromagnet coil 4 causes the armature to vibrate' due to the attraction lbetween the pole pieces and the magnetic material of the armature. Thus, during one half cycle of the ringing current applied to coil 4, the upper end" of core 5 is a northpole attracting the armature and shortening gap g1 and the lower end becomes a' south .pole repelling the armature and lengthening gap g2. The drive rod swings to left driving Ithe clapper 46 against the spring stress of shaft to strike gong Gl Duringvth'e next hal-f cycle of the ringing current the upper end of core 5 is a south pole repelling the armature and lengthening gap g1.l The lower end of core 5 is a north pole attracting the armature and shortening gap g2. Responsive thereto the drive rod'lswings to the right as viewed in F-iGS. 1 Vand 2. The resulting release of spring stress on shaft 45 and ythe inertia of clapper assembly 26 causes clapper 46 to strike gong G2.

The frequency at which the pendulum assembly A vibrates can be regulated by varying the position and the mass .of the inertia means, weight 40, attached to the drive rod 27. Thus, the mechanically tuned system constitutes a driven means and is composed of inertia means 40, driverod 27, armature 25 and reed spring 34, which is adjusted to vibrate at the frequency which is equivalent to the resonant frequency of .the electrical system consisting of a capacitor (not shown) and coil 4of the electromagnet. Drive rod 27 is physically in contact with flexible shaft 45 at point x and therefore causes the driven means, in this embodiment of the invention the clapper assembly (FIG. 5) to vibrate. Since the mass and spring constant of the clapper assembly is much less than that of the drive assembly, the amplitude of the vibration of the cla-pper assembly is larger than that of the drive assembly. Therefore, only clappe'r 46 strikes the gongs and at a point on the gongs which results in the maximum sound output. Also the Ilow inertia of the clapper assembly minimizes going damping. Thus, this ringer provides pleasing tones.

Another advantage of the present invention is the frequency stability it provides. This stability results from the fact that the amplitude of the movement of the tuned driving assembly is lowered by the damping due to the clapper unit and therefore its amplitude is almost independent of the driving voltage variations. The clapper assembly is actuated by the driving assembly and not by the voltage input. Also, stability is increased because the wear on the clapper does not affect the frequency since the mechanica-l frequency is determined by the tuned drive assembly and is largely independent of the high mechanical frequency of the clapper assembly. Still another advantage of this invention that is derived because the clapper assembly which strikes the gongs is mechanically separated from the turned frequency determining drive unit so that .the change in resonant frequency of the clapper assembly which occurs due ito the addition `of gong reactance when the clapper strikes the gong has no .affect on the input frequency.

Still another advantage derived from the present invention is the improved frequency sensitivity it affords. This is because the lightweight clapper assembly has a much higher amplitude swing than the tuned driving rod and, therefore, a comparatively small voltage is required to cause the clapper to strike the gong.

The ringer described herein also has a high selectivity because of the unique mechanical coupling of tuned systems wherein the resonant yfrequency of the ringer can be varied by changing the spring constant and mass of each system used therein. These variables can be selected to maximize selectivity. It should be noted that the ringer may easily and quickly be tuned to the desired frequency without regard to the spacing of the gongs by adjusting the position and size of the inertia means. That is because dynamically the resonance of the drive unit determines the frequency to which the ringer will respond, while the resonance of the clapper assembly does not affect the ringer system, so that when .the clapper unit strikes the gong and is thereby detuned, there is no adverse effect.

While I have described the above principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention.

I claim:

l. A frequency selective electromechanical rin-ger for producing audible signals responsive to the receipt of electrical signals having a certain frequency comprising a frame, at least one ringer bell, armature means, means ,for resiliently supporting said armature means on said frame, electromagnetic means operated responsive to the receipt of said electrical signals and causing said arma- -ture to respond as a function of the said certain frequency, .clapper assembly means mQVably mounted on said frame,

E and drive means attached to said armature for mechanically tuning Isaid arma-ture to said certain frequency and for driving said .clapper assembly means to repeatedly strike lsaid bell and thereby produce said audible signals.

2. A frequency selective ringer comprising a frame having -at least one gong mounted thereon, means for striking said gong responsive to the receipt of a signal having any of a .plurality of ringing frequencies, means comprising a drive rod and clapper assembly for tuning said ringer -to respond to only a selected one of said frequencies, said tuning means comprising an armature resiliently mounted on said frame and having said drive rod rigidly attached thereto, and a flexible shaft having one end attached to said `frame and the other end attached to said striking means positioned adjacent to said gong, said rod engaging said shaft :for imparting mechanical motion to said striking means responsive to movement of said armature.

3. A ringer clapper assembly comprising a tuned pendulum having a rigidly mounted supporting structure, an armature resiliently mounted on said supporting structure for vibrating rela-tive to said structure, a first pendulum comprising a rigid rod slidably supporting an inertia weight, said rod being integrally mounted on said armature to vibrate in unison with said armature, and a second pendulum comprising a flexible shaft having one end secured to ysaid supporting structure and the other end secured to a weight, said flexible shaft having a configuration to mechanically engage and spring bias said first pendulum to a normal position.

4. A frequency selective electromagnetic ringer having a frame, sounding means mounted on `said frame, an armature, resilient means for movably supporting said armature on said frame; a substantially rigid rod attached to said armature, means comprising an inertia means adjustably positionable along said rod for acting in cooperation with said resilient supporting means to tune said armature to a selected frequency, a clapper assembly attached to said iframe and normally positioned in mechanical abutment with said rod, said clapper assembly comprising a clapper weight mounted on a flexible shaft, and electromagnetic means operated respon-sive to signals having said selected frequency for actuating said armature to drive said rod whereby said rod causes said clapper to cyclically strike said sounding means thereby producing an audible ringing signal.

5. In the frequency selective electromagnetic ringer of claim 4 wherein means .are provided for varying the loudness of said ringing signal.

References Cited by the Examiner UNITED STATES PATENTS 2,209,382 7/40 Blattner 340-397 2,692,380 10/54 Cleaveland 340-401 2,733,435 1/56 Bredehoft 340-397 2,844,767 7/58 Houdek 317-177 NEIL C. READ, Primary Examiner.

BENNETT G. MILLER, Examiner. 

1. A FREQUENCY SELECTIVE ELECTROMECHANICAL RINGER FOR PRODUCING AUDIBLE SIGNALS RESPONSIVE TO THE RECEIPT OF ELECTRICAL SIGNALS HAVING A CERTAIN FREQUENCY COMPRISING A FRAME, AT LEAST ONE RINGER BELL, ARMATURE MEANS, MEANS FOR RESILIENTLY SUPPORTING SAID ARMATURE MEANS ON SAID FRAME, ELECTROMAGNETIC MEANS OPERATED RESPONSIVE TO THE RECEIPT OF SAID ELECTRICAL SIGNALS AND CAUSING SAID ARMATURE TO RESPOND AS A FUNCTION OF THE SAID CERTAIN FREQUENCY, CLAPPER ASSEMBLY MEANS MOVABLY MOUNTED ON SAID FRAME, AND DRIVE MEANS ATTACHED TO SAID ARMATURE FOR MECHANICALLY TUNING SAID ARMATURE TO SAID CERTAIN FREQUENCY AND FOR DRIVING SAID CLAPPER ASSEMBLY MEANS TO REPEATEDLY STRIKE SAID BELL AND THEREBY PRODUCE SAID AUDIBLE SIGNALS. 